An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves and performs a threshing operation on the crop to remove the grain. Once the grain is threshed it falls through perforations in the concaves onto a grain pan. From the grain pan the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. A cleaning fan blows air through the sieves to discharge chaff and other debris toward the rear of the combine. Non-grain crop material such as straw from the threshing section proceeds through a residue system, which may utilize a straw chopper to process the non-grain material and direct it out the rear of the combine. When the grain tank becomes full, the combine is positioned adjacent a vehicle into which the grain is to be unloaded, such as a semi-trailer, gravity box, straight truck, or the like; and an unloading system on the combine is actuated to transfer the grain into the vehicle.
To remove crop material from the field, the header of the combine harvester may be equipped with a cutter bar assembly having many sharp cutting elements that reciprocate sidewardly, relative to a forward direction of travel, to sever the crop material from the field before entering the feeder housing. The header may include a rotating reel with tines or the like to sweep crop material toward the cutting elements.
A conveyance system can be carried rearwardly of the cutting elements. Two different conveyance systems are widely used to transport cut crop material toward a center of the header before proceeding to the feeder housing. The first type of conveyance system utilizes a pair of cross augers which counter-rotate to convey crop material from sides of the header toward the center. The other type of conveyance system utilizes a rotating belt, which can be referred to as a draper belt, to convey material from sides of the header toward the center. When a draper belt is used to convey crop material toward the center of the header, the header can be referred to as a “draper header.”
A draper header is typically used to harvest fluffy or bushy crop material such as soy beans or canola. Many draper headers include two lateral draper belts that convey the crop material longitudinally inward and a center feed belt that conveys the crop material into the feeder housing. Each draper belt may be wrapped around rollers, for example various combinations of drive rollers and idler rollers. The draper belts may include cleats extending transversely across the full width of the header, which contact the crop material to help facilitate its transportation into the feeder housing.
In many draper header configurations, the cutter bar assembly is supported by a frame of the draper header which also supports an interior of the draper belt which does not generally contact crop material. Since cut crop material tends to fall on a top of the draper belt during harvesting, supporting the bottom of the draper belt with the frame helps the draper belt keep its shape during harvesting. In many draper head configurations, the frame also connects the cutter bar assembly and associated cutting elements to the chassis of the combine.
One particular problem of known draper headers occurs when the cutter bar assembly collides with a relatively immobile object. When the collision occurs, the frame of the header can be damaged due to force transmission through the frame. In many cases, the damage that occurs to the frame is not easily and/or inexpensively repaired; in some cases, the damage to the frame is so extensive that the entire header must be replaced.
To limit damage to the frame that may occur when the cutter bar contacts an immobile object, some header constructions incorporate springs which compress during impact. While the springs may be effective to limit frame damage, the tendency of the springs to compress and rebound during normal crop harvesting operations can cause a large amount of movement by the frame, and especially the cutter bar, which detrimentally affects the consistency of the cut by the cutting elements. Further, it is difficult to adequately support the cutter bar when using springs to limit damage since the springs alone cannot adequately support the cutter bar against the force of gravity if the deformation and rebounding of the springs tends to occur parallel to the travel direction of the combine.
What is needed in the art is a header which is less prone to structural damage than known constructions while still allowing for a consistent cut during harvesting.